ATTORNEY-General George Brandis strongly argued against world-first laws banning paedophiles from travelling overseas for child sex holidays during "robust" Cabinet meetings that left colleagues questioning his political judgment.

In a rare Cabinet leak, three ministers present confirmed Senator Brandis objected to further penalties on offenders because their crimes had already been dealt with by the courts.

Senator Brandis was not being soft on child sex offenders but mounted a vigorous, technical legal argument about the role of government, executive and judiciary, The Courier-Mail has been told.

The embarrassing Cabinet breach comes as tension and frustration mounts within the Coalition over a looming reshuffle, the gay marriage survey which will be challenged in the High Court from tomorrow, the citizenship debacle and allegations of undermining.